linux-kernel - Re: [PATCH] perf, tools: Fix perf stat --per-core on multi socket systems

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Date:	Fri, 26 Sep 2014 12:33:27 +0200
From:	Stephane Eranian <eranian@...gle.com>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	Jiri Olsa <jolsa@...hat.com>, LKML <linux-kernel@...r.kernel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH] perf, tools: Fix perf stat --per-core on multi socket systems

On Wed, Sep 24, 2014 at 10:50 PM, Andi Kleen <andi@...stfloor.org> wrote:
> From: Andi Kleen <ak@...ux.intel.com>
>
> On systems with more than one socket perf stat --per-core
> would either segfault or stop before outputting all cores.
> The problem was that the output code referenced the
> id including the socket number in the higher bits, which
> is far beyond any per cpu array.
>
> Mask out the socket number before referencing cpus
> in abs_printout.
>
> I also renamed the variable in nsec_printout to be clear
> what it is, even though it doesn't reference cpus.
>
> Cc: eranian@...gle.com
> Signed-off-by: Andi Kleen <ak@...ux.intel.com>

This works for me and is the better approach compared to what
I saw in Matt Flemming's patch: https://lkml.org/lkml/2014/9/24/571

Acked-by: Stephane Eranian <eranian@...gle.com>

> ---
>  tools/perf/builtin-stat.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> index 3e80aa1..6e636b9 100644
> --- a/tools/perf/builtin-stat.c
> +++ b/tools/perf/builtin-stat.c
> @@ -732,7 +732,7 @@ static void aggr_printout(struct perf_evsel *evsel, int id, int nr)
>         }
>  }
>
> -static void nsec_printout(int cpu, int nr, struct perf_evsel *evsel, double avg)
> +static void nsec_printout(int id, int nr, struct perf_evsel *evsel, double avg)
>  {
>         double msecs = avg / 1e6;
>         const char *fmt_v, *fmt_n;
> @@ -741,7 +741,7 @@ static void nsec_printout(int cpu, int nr, struct perf_evsel *evsel, double avg)
>         fmt_v = csv_output ? "%.6f%s" : "%18.6f%s";
>         fmt_n = csv_output ? "%s" : "%-25s";
>
> -       aggr_printout(evsel, cpu, nr);
> +       aggr_printout(evsel, id, nr);
>
>         scnprintf(name, sizeof(name), "%s%s",
>                   perf_evsel__name(evsel), csv_output ? "" : " (msec)");
> @@ -947,11 +947,12 @@ static void print_ll_cache_misses(int cpu,
>         fprintf(output, " of all LL-cache hits   ");
>  }
>
> -static void abs_printout(int cpu, int nr, struct perf_evsel *evsel, double avg)
> +static void abs_printout(int id, int nr, struct perf_evsel *evsel, double avg)
>  {
>         double total, ratio = 0.0, total2;
>         double sc =  evsel->scale;
>         const char *fmt;
> +       int cpu = cpu_map__id_to_cpu(id);
>
>         if (csv_output) {
>                 fmt = sc != 1.0 ?  "%.2f%s" : "%.0f%s";
> @@ -962,7 +963,7 @@ static void abs_printout(int cpu, int nr, struct perf_evsel *evsel, double avg)
>                         fmt = sc != 1.0 ? "%18.2f%s" : "%18.0f%s";
>         }
>
> -       aggr_printout(evsel, cpu, nr);
> +       aggr_printout(evsel, id, nr);
>
>         if (aggr_mode == AGGR_GLOBAL)
>                 cpu = 0;
> --
> 1.9.3
>
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